The options above use the default two-level namespace on OS X and change name resolution to run-time resolution.

Using those options doesn’t seem to have any ill effects but I’m curious why LLVM doesn’t do that already, especially considering many other dynamic libraries for Mac OS X are compiled using the new options specified above. In fact, the former options actually seem to be remnants from pre-10.3 days. Just in case, I’ve asked that very question on the LLVM-dev mailing list.